Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Repercussion

Whenever a creature is dealt damage, Repercussion deals that much damage to that creature's controller.

Compost

Whenever a black card is put into an opponent's graveyard from anywhere, you may draw a card.

Hansk, Slayer Zealot

At the beginning of your upkeep, target opponent creates three Walker tokens. (They're 2/2 black Zombie creatures.)
{T}: Hansk, Slayer Zealot deals 2 damage to target creature.
Whenever a Zombie an opponent controls dies, draw a card.

Aether Flash

Whenever a creature enters, Aether Flash deals 2 damage to it.

Thornbite Staff

Equipped creature has "{2}, {T}: This creature deals 1 damage to any target" and "Whenever a creature dies, untap this creature."
Whenever a Shaman creature enters, you may attach Thornbite Staff to it.
Equip {4}

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)